Loud-speaker apparatus



1932- w. c. BIDWELL ET AL 1,391,968

' LOUD SPEAKER APPARATUS Filed Feb. 25, 1932 Patented Dec. 27, 1932 UNITED STATES PATENT; OFFICE C. BIDWELL AND ALBERT L. CUTLER, F PORTLAND, OREGON f LOUD-SPEAKER APPARATUS" This invention relates to improvements loud-speaker apparatus, and has for its principal objectthe provision of novel and efii-,

cient apparatus associated with the loud,- speaker mechanismfor modulating the emitted amplified sound vibrations to maintain the true pitch and natural reproduction of the original tones throughout the entire sound register audible to the ear.

A further object of the invention is to provide sound-modifying apparatus of simple and practicable construction including a sound-board to which the speaker-cone is connected, and a tone-box arranged interiorly and in intimate contact with the soundboard, such apparatus in its assembly and combination affording a marked betterment in the quality and fidelity of tone produced by loud-speakers and admitting of greatly 0 amplified volume without distortion from the original sound impulses.

A still further object of the invention consists in the provision of a sound-board in conjunction with a loud-speaker and particularly in the especial form thereof embodied in the present disclosure whereby a board of relatively large size and capacity may be employed without unduly increasing the size of the loud-speaker apparatus.

Other objects and advantages residing in our invention, and objects relating to details of construction and arrangements of parts thereof, will be readily apparent in the course of the following detailed description.

The accompanying-drawing illustrates by way of example a representative form of our invention, in which:

Figure l is a perspective view ofloud- 0 speaker apparatus embodying our invention,

shown mounted in a supporting frame.

Fig. 2 is a view in longitudinal vertical section, being shown upon an enlarged scale and removed from the supporting frame. v Fig. 3 is a view in front elevation with the horn removed.

Fig. 4 is a view in 4-4 of Fig. 2. 2 Referring to said views, the reference nu- 0 meral 1 indicates the base-board of our imvertical section on line proved sound modulating apparatus for loud-speakers- Said base-board is formedof wood of approved resonant qualities and is desirably rectangular in configuration with its opposite sides in parallel planes. It is provided with an axially disposed circular 5 1 aperture 2 about whose periphery on its inner side the flange 3 of'a loud-speaker cone 4 is secured in the usual manner with a cushion gasket 5 interposed therebetween. The loudspeaker apparatus is shown at 6 extending rearwardly from'the speaker-cone. p

c Secured to the perimeter of the base-board 1 in tightly dowelled and cemented condition so as to be for the purposes of sound-vibration homgeneous is an extension disposed in rightangled relationthereto and consisting of top and bottom walls 7 and 8 and opposite side walls 10. The base-board joins the rectangular extension on a line spaced inwardly from the forward edge of the extension to provide 7 arelatively shallow, o en-front chamber 11 forwardly of thebaseoard.

Spaced rearwardly from the base-board 1 a partition-board 12 is joined at its outer rectangular edges to the extension-walls 7, 7

8 and 10 in parallel with the base-board and provides a chamber 13 at its rear within the overhanging walls of the extension, said chamber being open at its rearward side. Said partition is formed witha square open- 3 ing 15 somewhat larger than the circular aperture 2'and disposed symmetrically with respect to the axis thereof and through which the loud-speaker apparatus 6 may project if desired.

Liner-boardslfi are rigidly secured in rectangular relation and parallel, respectively, to the extension-Walls 7, 8 and 10, between the base-board 1 and the partition'12 laterally enclosing the .speaker-chamber17 and forming exteriorlythereof the tone-box 18 extending uninterruptedly entirely about the interior of the extension-walls and the outer portion of the base-board. Said tone-box is entirely enclosed excepting for a plurality of exterior. surface of the base-board about the opening 2 and extends flaringly to beyond the limits of the forward chamber 11. At the rear of the apparatus and spaced from the rear edges of the extension-walls is a reflectordisc of substantially concavo-convex form and within whose concavity the rear edges of the extension walls may extend. Said reflec tor-disc may be formed of any suitable highly reverberatory material and is supported upon wooden arms 22 secured in the angles of the liners 16 and projecting rearwardly of the chamber 13.

The apparatus may be mounted in any desired manner but advantageously may be supported within a skeleton metal frame 23 being suspended therein by flexible or elastic straps 25, whereby the apparatus is in a manner insulated from exterior causes and its acoustical properties thereby unaffected.

It will be noted that the base-board 1 and extension-walls 7, 8 and 10 are practically homogeneous and integral and form collectively a sound-board of extended area in rela tively small compass. The tone-box 18 of which the sound-board forms two walls serves to modulate and control the vibratory action of the sound-board and maintain the soundwaves issuing therefrom in faithful reproduction of the original tones and to reproduce the sound impulses of vibratory frequencies at their true pitch regardless of the volume at which the sound-waves may be amplified.

Additional tonal and sustaining qualities are provided through the utilization of the reflector-disc 26 which is so disposed as to reverberate forwardly practically all of the sound-waves ordinarily directed to the rear and projecting them with directional effect in parallel with the sound-waves emitted by the horn and thus avoiding adverse acoustical eifects from echoes issuing from a wall or other surface located at the rear of the apparatus. Thus such rearwardly directed sound-waves are reflected forwardly and strike the ear of the auditor at substantially the same interval of time as those issuing from the horn.

Having described our invention, what we claim, is

1. Loud-speaker apparatus, consisting of a baseboard of rectangular configuration, extensions to said base-board directed in rightangled relation from the respective edges thereof, a loud-speaker secured to said baseboard about its approximate center axis, and walls directed from said base-board and extension, respectively, enclosing a tone-box surrounding said loud-speaker.

2. Loud-speaker apparatus, consisting of a base-board formed with an opening, a loudspeaker mounted about said opening in the base-board, an extension to said base-board extending at approximate right angles to the base-board, and a tone-box disposed within the angle formed by said base-board and extension and surrounding said loud-speaker.

3. Loud-speaker apparatus, consisting of a base-board formed with a central opening and a plurality of smaller apertures thereabout, a loud-speaker having its cone secured about said opening in the base-board, an extension to said base-board extending at approximately at right angles to the base-board, and a tone-box disposed within the angle formed by said base-board and extension to whose chamber said apertures of the baseboard communicate.

4. Loud-speaker apparatus, consisting in a sound-board having a relatively vertical base-board of rectangular configuration and extensions extending in right angled relation thereto from its respective edges, said baseboard having an opening therein and a plurality of smaller apertures spaced radially therefrom, a loud-speaker havin its cone sccured about said opening, a toneox dis osed within the angle formed by said baseoard and extensions, and a reflector-disc mounted rearwardly of said extension and spaced therefrom.

5. Loud-speaker apparatus, consisting in a base-board formed with a central opening, extensions to the periphery of said base-board extending at right-angles thereto, a tone-box disposed within the angles formed by said base-board and extensions and formin a central space within which the loud-spezilcer is positioned, and said speaker secured to said base-board with its cone secured about said opening.

6. Loud-speaker apparatus, consisting in a base-board formed with a central opening, extensions to the periphery of said base-board extending at right-angles thereto, a tone-box disposed within the angles formed by said base-board and extensions and providing a central space within which the loud-speaker is positioned, said speaker secured to said base-board with its cone secured about said opening, and a reflector-disc secured in spaced relation at the rear of said extensions.

7. In loud-speaker apparatus, a soundboard device consisting of a base-board, an extension therefor extending at approximately right-angles to the base-board, said extension extending at both front and rear of the base-board to provide chambered portions upon opposite sides of the base-board, and a tone-box disposed in the rear of said chamber and in the angle formed by said base-board and extension.

8. In loud-speaker apparatus, a soundboard device consisting of a base-board having an opening therein, a loud-speaker having its sound-cone secured to said base-board about the perimeter of said opening, a tonebox mounted on said base board' and having sound-apertures extendingthrough the baseboard, and a horn extending forwardly from said opening in the base-board.

9. In loud-speaker apparatus, a soundboard consisting of a base-board having an opening therein, a loud-speaker havin its sound-cone secured to said base-board a out the perimeter of said opening, said base-board having an extension from its edges extending forwardly and rearWardly at approximately right-angles thereto, a tone-box formed in the 7 angle between said base-board and its rear extension, a horn extending forwardly from said opening in the base-board, and a refiector disc rigidly mounted in spaced relation to the rear of said rearwardly directed extension.

10. In loud-speaker apparatus, a soundboard consisting of a base-board having an opening therein, a loud-speaker having its 2 sound-cone secured to said base-board about the perimeter of said opening, said base-board havin an extension fromits edges extending forwardly and rearvvardly at approximately right-angles thereto, a tone-box formed in the I angle between said base-board and its rear extension, and a horn extending forwardly, from said opening in the base-board.

11. In loud-speaker apparatus, a baseboard having a central aperture, a rearwardly extending extension from said base-board directed at approximately right angles thereto, a loud-speaker having its sound cone secured to said base-board about the perimeter of said opening, and a reflector-disk mounted 36 in spaced relation to the rear of said rearwardly directed extension. 7 1. In loud-speaker apparatus, a baseboard having a central aperture, a rearwardly extending extension from said base-board 40 directed at approximately right angles thereto, a loud-speaker having its sound-cone secured to said base-board about the perimeter of said opening, and a reflectondisk'mounted in spaced relation to the rear of the rear- Wardly directed extension and having its 7 perimeter extending outwardly of said extension.

WILLIAM C. BIDWELLQ ALBERT L. CUTLER. 

